This invention relates to pumpable cement grouts or mortar compositions and a process for their manufacture. More particularly, this invention relates to improvements in cement grouts or mortars which contain additives which improve the workability while reducing the tendency of the cement to segregate, bleed or shrink before hardening.
In the use of pumpable grouts or cements, invariably, a cement factor of upwards of eight sacks per cubic yard is used. In preparing such pumpable cements or grouts, it is desirable to disperse the cement particles thoroughly, reduce water requirement while increasing fluidity, reduce bleeding and segregation and control expansion and/or reduce setting shrinkage. Attempts to improve cement grouts or mortars generally have been directed to improving pumpability, penetration, strength, durability and bonding to reinforcing steel.
Additives have been suggested in the prior art for improving the desirable properties of cement grouts and mortars. Calcium chloride has been suggested and has been demonstrated to provide high early strengths. However, calcium chloride has exhibited a tendency to reduce expansion excessively, particularly when used in combination with aluminum powder which previously has been described as an additive for cement grouts. Sodium chloride has been suggested as an accelerator for high water, low strength cements and bituminous-containing grouts.